Biomaterial Database

Calcium-binding characteristics of the EDTA-extractable proteins from calf lens fiber membranes. 1985

A J van den Eijnden-van Raaij, and A L de Leeuw, and R M Broekhuyse

The calcium-binding characteristics of the EDTA-extractable proteins (EEP) from calf lens fiber membranes were studied by equilibrium dialysis and far-ultraviolet circular dichroism measurements. The EEP proteins appeared to contain binding sites with different affinities for calcium. These sites seem to behave as positively cooperating Ca2+ binding sites with a total capacity of 25 mol Ca2+ per mol EEP. The mean apparent dissociation constant (KD) for the Ca2+ binding sites was determined to be 7.7 microM. Calcium binding probably is accompanied by a decrease in the apparent alpha-helical content of the EEP proteins. The present results indicate that the EEP proteins belong to the group of proteins possessing high affinity and binding capacity for calcium. Because of the high calcium-binding capacity, the EEP proteins possibly function as an intracellular calcium store in the lens. The calcium-sensitivity of the conformational state of the EEP proteins, however, might point to a possible regulating function of these membrane proteins in calcium-dependent cellular processes in the lens.

UI	MeSH Term	Description	Entries
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002417	Cattle	Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.	Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D003956	Dialysis	A process of selective diffusion through a membrane. It is usually used to separate low-molecular-weight solutes which diffuse through the membrane from the colloidal and high-molecular-weight solutes which do not. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Dialyses
D005136	Eye Proteins	PROTEINS derived from TISSUES of the EYE.	Proteins, Eye
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia